平原水库浸没地下水临界埋深分析

平原水库蓄水易产生水库浸没,危害周围农作物和建筑物,需确定平原水库地下水临界埋深。对于农作物,水库浸没导致农作物发生渍害和次生盐渍化,利用作物根系层厚度计算防止农作物发生渍害的临界埋深;引入矿化度级差计算防止土壤次生盐渍化的临界埋深,选取两者最大值作为农作物浸没临界埋深。对于建筑物,引入弹塑体结构计算模型,根据承载力与地基应力的关系计算承载力影响下的临界埋深,根据应力分层总和法确定受附加应力影响的临界埋深,最后利用层次分析法计算权重大小,综合考虑各因素确定建筑物浸没临界埋深。通过提出地下水临界埋深评价方法为减轻浸没危害、预测库区可能发生浸没的地区范围提供了依据。     

旬阳钟家坪水电站溢流坝的面流消能设计与试验

研究了旬阳钟家坪水电站溢流坝的面流消能问题,通过分析确定了合理的溢流坝跌坎高度、鼻坎挑角和反弧半径等参数,并对下游水面线、水面波动和流速分布等情况进行了试验研究,为面流消能设计提供了依据,保证了设计的可靠性。     

End Effect on the Twin—Wire Depth Probe

The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and ex-perimentally.It was found that the contribution of the end of the probe to the output voltage depends uponthe distance between the boundary and the end of the probe and the geometrical configuration of the probe.By mounting a piece of plate to the end of the electrodes,the end effect can be reduced.However,the size ofthe plate required to eliminate completely this effect is much larger than that usually mounted on commerciallyavailable probes.Comparison between theoretical and experimental results was made.Reasonable agreementwas obtained.     

Simple modelling of the effects of exploitation on hot springs, Geyser Valley, Wairakei, New Zealand

Many hot springs in Geyser Valley declined and ceased flowing during well testing (1950–1958) or the early stages of development (1958–1964) of the Wairakei field, North Island, New Zealand. A simple model that considers mixing, geothermal reservoir pressure, and Darcy flow is applied to analyse the changes in flow rate and chemistry of spring SP18. The model suggests that prior to the testing the observed flow rate of 3 l/s was comprised of about 2.1 l/s of water from the deep reservoir and about 0.9 l/s from shallow groundwater. As the pressure in the reservoir decreased as a result of exploitation, the reservoir component declined but the groundwater component remained near constant until the spring had nearly ceased flowing. The model reasonably predicts the flow cessation date for four other springs (Group A) but poorly predicts that for seven other springs (Group B). These two groups of springs do not appear to be clustered at the ground surface. The pressure–elevation relationship suggests that the Group A springs feed from within the shallower Waiora Formation and Group B springs from within the deeper Wairakei Ignimbrite Formation. The observation that declines of chloride concentrations in Group A springs occurred at least three years before those in springs of Group B is consistent with the finding that Group A springs have a shallower feeder depth.     

Influence of growth conditions on the V-defects in InGaN/GaN MQWs

The influence of the growth temperature,TMIn/TEGa andⅤ/Ⅲratio on the V-defects of InGaN/GaN multi-quantum wells（MQWs） has been investigated and discussed.When the TMIn flow increases from 180 to 200 sccm,the density of V-defects increases from 2.72×10¹⁸ to 5.24×10¹⁸ cm^-2,and the V-defect width and depth increase too.The density also increases with the growth temperature.The densities are 2.05×10⁸,2.72×10¹⁸ and 4.23×10⁸ cm^-2,corresponding to a growth temperature of 748,753 and 758℃respectively.When the NH₃ flows are 5000,6600 and 8000 sccm,the densities of the V-defects of these samples are 6.34×10¹⁸,2.72×10¹⁸ and 4.13×10¹⁸ cm^-2,respectively.A properⅤ/Ⅲratio is needed to achieve step flow growth mode.We get the best quality of InGaN/GaN MQWs at a growth temperature of 753℃TMIn flow at 180 sccm,NH₃ flow at 6600 sccm,a flatter surface and less V-defects density.The depths of these V-defects are from 10 to 30 nm,and the widths are from 100 to 200 nm.In order to suppress the influence of V-defects on reverse current and electro-static discharge of LEDs,it is essential to grow thicker p-GaN to fill the V-defects.     

片式薄膜电容切片工艺及设备研究

在多种电子元器件中,电容器是使用面最广和用量最大的电子元件。片式薄膜电容器是由薄膜电容条切割而成,切片工艺是片式薄膜电容器生产中的关键工艺。介绍了叠层薄膜电容器的生产工艺。着重论述了切片工艺研究内容,并根据研究所得工艺开发出了相关设备,对设备的关键技术提出了解决办法。     

A comparative research on magnetron sputtering and arc evaporation deposition of Ti-Al-N coatings

Ti-Al-N coating has been proven to be an effective protective coating for machining applications. Here, the differences of cubic Ti-Al-N coatings with a similar Ti/Al atomic ratio of 1 deposited by magnetron sputtering and cathodic arc evaporation have been studied in detail. Main emphasis was laid on the characterization of thermal stability and cutting performance. Both coatings during annealing exhibit a structural transformation into stable phases c-TiN and h-AlN via an intermediate step of spiondal decomposition with the precipitation of c-AlN, however, a difference in decomposition process. Compared to sputtered coating inserts, an increase of tool life-time by 42% is obtained by evaporated coating inserts at the higher speed of 200 m/min, whereas the similar cutting life is observed at the speed of 160 m/min. It is attributed to the better stability of evaporated coating due to its later structural transformation at elevated temperature. A post-deposition vacuum annealing of both coated inserts in their corresponding temperature range of spiondal decomposition improves their cutting performance due to an increase in hardness arising from the precipitation of coherent cubic-phase nanometer-size c-AlN domains. Additionally, the sputtered coating behaves in worse oxidation resistance due to its more open structure. These behaviors can be understood considering the difference in microstructure and morphology of as deposited coatings originating from adatom mobility of deposited particles, where arc evaporation technique with higher ion to neutral ratio shows higher adatom mobility.     

混凝土在弯曲应力作用下碳化进程的研究

研究了混凝土试件在弯曲应力作用下截面的碳化进程以及碳化深度与裂缝几何形态的相关关系.研究结果表明:在弯曲应力作用下,截面开裂部分的碳化深度明显高于未开裂和受压区的碳化深度,但裂缝内部的碳化深度与裂缝的表面张开宽度并无明显相关关系,试验数据统计结果显示裂缝对碳化深度的放大系数为2.08.同时比较了弯曲裂缝内部碳化深度测量...     

土壤源热泵地下换热器热阻模型的对比分析

本文基于经典的线源理论和圆柱源理论,求解了土壤源热泵地下换热器的各项热阻。结合热阻概念,建立热平衡方程求解了单位深度换热量。分析了系统运行时间、管内水流速、回填材料导热系数、冬夏季进口水温和岩土类型对热阻和单位深度换热量的影响,为地源热泵系统的优化设计提供参考。     

户型布局对住宅小区容积率影响研究

对两种户型布局方式进行了简要介绍,并通过假设条件和住宅小区简化模型,求出在同一小区中布置两种户型后容积率的比值,从而得出户型的长宽比越小容积率越大的结论,并对此结论的适用性进行了说明,对规划设计和房地产企业开发决策有参考意义.